Acoustic telemetry involves acoustic devices called acoustic tags that are commonly used to monitor behavior of fish. Acoustic tags transmit a sound signal or acoustic “ping” that sends identification information and location information about a tagged fish to a receiver. The receiver converts sound signals into digital data. Post processing software processes the digital data and provides positions of the tag when the receiver detects the same sound signal. By determining the sound's time of arrival at the hydrophone receiver, the position of the tag can be determined, allowing tracking of the host animal. Then, by tying the acoustic signature received from the transmitter to the programmed signal code, a specific animal may be identified. Acoustic telemetry has been used to observe behavior and assess survival of juvenile Chinook salmon as well as understand the biological effects of implantation of acoustic tags in yearling and sub-yearling Chinook salmon. Development of autonomous and cabled receiving systems deployed at dams and elsewhere in rivers has also been studied. Receiving systems detect signals emitted by the acoustic tags, process the resulting detection data to track the fish, and provide data necessary to estimate survival through dams and other routes of passage. Together, the acoustic tags and receiving systems in the Columbia River system make up the Juvenile Salmon Acoustic Telemetry System (JSATS). Although acoustic tags presently used for JSATS meet current tag burden guidelines for most yearling Chinook salmon, the tags are too large for smaller juvenile Chinook salmon, particularly those found in the lower Columbia River and estuary that enter the river downstream of the Bonneville Dam. Bioeffects studies also indicate that juvenile Chinook salmon less than 95 mm in length (approximately 9 g weight) implanted with current acoustic tags have reduced survival and growth rates. Accordingly, new tag designs are needed that reduce the overall size, weight, and volume, enhance the range and lifetime, reduce adverse effects associated with implantation, and broaden the range of potential applications. The present invention addresses these needs.